Four-blade rigid main rotor. Hub and
inboard portion of flexible blade attachment arms made from a single
mono-block titanium forging. Blade pitch is controlled via 'spider' arms
that protrude out of the main rotor mast below the hub. The central shaft
of the 'spider' is running down the mast through the main gearbox where
three hydraulic actuators connect to its lower end.

Four blade stacked system with two
teetering yokes in scissor arrangement and elastomeric flapping bearings.
Composite blades with swept blade tips and Nickel-Cobalt leading edge
abrasion strips,

Boeing Helicopters

Boeing AH-64A/D Apache

Four-blade hybrid main rotor
with kinematic lead-lag hinges. Blade pitch housings connected to rotor
hub by single combined elastomeric bearings that allow for axial, flapping
and feathering motion. These quasi flap hinges/feathering bearings are
offset 4% from the main rotor axis for increased control power. Blades
attached to hub by V-shaped 22-ply laminated steel packs that are stiff in
the lag plane but flexible towards flapping and torsion. Two elastomeric
lead-lag damper packs per blade.

Four-blade rigid main rotor. Hub and
inboard portion of flexible blade attachment arms made from a single
mono-block titanium forging. Blade pitch is controlled via 'spider' arms
that protrude out of the main rotor mast below the hub. The central shaft
of the 'spider' is running down the mast through the main gearbox where
three hydraulic actuators connect to its lower end.